In addition to the boot prompt, there are two situations in which the horn will ring:
1, repeatedly press the key (including mouse and keyboard).
2, hardware problems, depending on what the sound is like, if it is a long sound, it is likely to be a memory problem; If it is a short tone, you can check whether the sound card, video card and kitten on the CPU and PCI slots are loose. I suggest you press the DEL key to enter the BIOS to see the system hardware status, CPU temperature warning and so on. If possible, you can check it with a hardware detection card. As I don't know the details of your question, you can try it first.